Bolt tool for use with tamperproof screw or the like



May 15, 1962 w. D. CORLETT ET AL, 3,034,386

BOLT TOOL FOR USE WITH TAMPERPROOF SCREW OR THE LIKE 2 Sheets-Sheet 1 Filed June 30, 1959 y 15, 1962 V w. D. CORLETT ET AL 3,034,386

I BOLT TOOL FOR USE WITH TAMPERPROOF SCREW OR THE LIKE Filed June 50, 1959 2 Sheets-Sheet 2 l ark K (Zr/er fi/zameys.

3,034,386 BOLT TOOL FOR USE WITH TAMPERPROOF SCREW OR THE LIKE Webster D. Corlett, River Forest, and Charles G. Mackie,

This invention relates to a tamperprocf screw and to a tool or wrench for applying it or for removing it. It

has for one object to provide a screw which is substantially vandalproof and which has no visible means for its removal after installation.

Another object is to provide a collet wrench having means, which may be flexible, for gripping the head of a screw or bolt which has a particular configuration not readily engageable by any conventional tool.

Other objects will appear from time to time during the course of the specification and claims.

The invention is illustrated more or less diagrammati cally in the accompanying drawings wherein:

FIG. 1 is an exploded, partial longitudinal section with parts shown in elevation;

FIG. 2 is an elevational view of the tool and screw before the screw is inserted showing parts of the assembly in section;

FIG. 3 is a transverse section taken at line 33 of FIG. 1;

FIG. 4 is a partial longitudinal section of the tool and screw after insertion of the screw, the view being taken on an enlarged scale with respect to the earlier figures;

FIG. 5 is an end elevation of the screw in the position of engagement by the tool; and

FIG. 6 is a transverse section taken at line 66 of FIG. 4.

Like parts are indicated by like numerals throughout the specification and drawings.

In the particular form here shown the screw of the invention is indicated by the numeral 1. It is externally threaded along its shank, as shown, and has a head portion 2. Beneath the head portion and adjacent the shank is a rounded or cylindrical enlargement 3. The

plurality of radially directed, outwardly extending projections or fingers 4 is positioned beneath the head. The fingers 4 terminate substantially at the outer periphery of the head 2 of the screw and their outer ends conform generally to the peripheral curvature of the head 2. A cylindrical enlargement 5 is positioned between the head 2 and the cylindrical enlargement 3. It is of greater diameter than the latter and the fingers 4 are substantially the same heightor thickness as the cylindrical portion 5. If desired the head may be beveled as at 6 and may have a flat portion 7 defining a substantial area of its top or upper portion. Preferably the peripheral edge of the head portion is circular, as indicated at S, and is uninterrupted and smooth, It is preferably also relatively thin 'in a vertical direction as shown in FIG. 1, and thus it is diiiicult to grip the edge by any tools such as pliers, wrenches and the like.

For purposes of illustration the screw may be indicated as adapted for insertion into a member 9 which is provided with a threaded hole 10. A cup 11 is provided, as shown, with upwardly extending walls and a bottom which is perforated as at 12 to provide an opening for the passage of the screw.

The tool in the form shown comprises a cylindrical section 13 with a plurality of integral spring arms 14 separated by cuts or slots 15 which extend to the bottom of the tool. The arms 14 are relatively thin as compared to the wall thickness of the cylindrical por- 3,034,386 Patented May 15,1962

tion 13. This is evident from the showing of FIGS. 1 and 4 in particular. Each arm portion is thickened adjacent its lower end as at 16 and the outer surface of each arm is beveled as at 17. The inner face of each arm below the thickened portion 16 is provided with a notch or groove 18 and a shoulder member 19. Thus, at the lower end of each arm a notch or groove 18 is bounded by the enlarged member 16 and the shoulder member 19. Preferably the lower face of the enlargement 16 is beveled as at 20.

The cylindrical member 13 is provided with axially aligned notches or grooves 21 which receive, preferably loosely, a plug member 22 which is of rectangular cross section. The plug member is retained in position within the tool by a pin 23.- It is important 'to recognize that the plug member 22 need not be of rectangular cross section as shown. It might be formed in other shapes, but in any event it will be made of angular shape and the parts of the tool .within which it fits will have corre sponding angular shape so that twisting of the plug within the tool is prevented.

As shown in FIG." 6 the plug 22 is engaged in notches or longitudinal grooves 24 in two of the arms 14 and rests against the face of the other arm 14. The inner faces of the arms throughout the enlargement 16 are thus shaped with flat or grooved or angular faces which, when the tool is in use, are in contact with the corresponding angular faces of the plug 22 and thus prevent twisting of the arms with respect to the remainder of the tool.

A sleeve 25 is provided about the tool and may slide from end to end of the tool. As shown in FIG. 1 it is in the uppermost or disengaged position. As shown in FIG. 4 it is in the lowermost or engaged position. It is provided with a knurled enlargement or thickened portion 26 and may be flared outwardly toward its lower end by means of a skirt formation 27. The contour of the skirt portion 27 internally is providedwith a surface 28 to cooperate with the beveled surface 17 on the exterior o f the arms 14. When the sleeve 25 is in the raised position the natural spring of the arms 14 causes them to move outwardly to the position shown in FIG. 1. The

arms are thus preferably biased to spring outwardly.

When the sleeve 25 is moved from the position of FIG. 1 to that of FIGS. 2 or 4 it forces the arms inwardly into the position shown in FIGS. 2 and 4, generally, and

it may be rotated. The size and cross sectional shape of the member 30 may be substantially the same as those of the plug 22 and the member 30, as well as the plug 22, fits into the longitudinal grooves or depressions 21 of the member 13. i

The use and operation of the invention are as followsi The screw, when installed, is a tamper-proof screw. Its head will not be readily engaged by any screwdriver or comparable tool. The periphery of the portion 8 is round and smooth and hence has no shape or part for ready engagement by a tool. The head of the screw itself when the parts are seated, as shown for example in FIG. 4, is well below the upper edge of the wall member of the cup 11. Hence the sides of the screw head are concealed and are extremely difficuit of access by any tool except the particular tool of this invention. The position of the-head of the screw within the cup 11 conceals it from ready inspection and the edge of the tool cannot be seen by the human eye looking into the cup because of the position of the head and the height of the wall 11 of the cup with respect to the screw head. Obviou ly inst ad of using t e p 1 the oc o member in whichthe screw isseated might have a counterbore. That is to say, the bore which is threaded could be positionedatthe bottom of a countenb'ore, hole or depression of sufiicient size and of proper proportion to accomplish the same result as that which is accomplished by the'wall 11 of the cup. The invention, while it is conveniently'used with the cup, is not limited'to that use and can be elfectively embodied where a counterbore is formed otherwise. i

When the screw is to beinserted it is moved into engagement with the arms 14 of the tool. The flange is fitted into the grooves or notches 18. Preferably the tool is so made that the arms must be. sprumg'into place. In

their normal position of rmt the arms are separated sufficiently so that they must be pushed somewhat farther apart to permit entrance of the screw head and to permit engagement of the screw head with the notches of the arms. When this engagement has taken place and the portions19 of the arms have fitted betweenthe members 4 .of the screw head, the tubular member is moved downwardly along the'tool from the position of FIG. 1 to that of FIGS. 2 and 4. 51H that position the arms are forced together and their lower ends are moved sulficiently together to hold the screw against displacement.

. in cross "section, and a plug'member positioned loosely Whether or not the lower ends'of the arms 14 tightly 2 grip the screw head is immaterial so longas they hold 'it against displacement and so long as they hold the parts 19 in position under the screw head 8 and between the members 4.

With the parts in the position just described the screw may now be inserted and the tool is ready for rotation.

' Rotation is accomplished by inserting the handle member 3.0, 31 in the upper end of the bore fonned within the tool 13 and rotation takes place. The screw is rotated into position and. when it has been forced as far in as is desired, rotation is stopped, the tubular member 25 plug prevents twisting or distortion of the spring arms 14 and insures a tighter engagement with the screw for rotation of the, screw. In the absence. of the plug 22 the tool may operate but there is a tendency to twist or distort the arms 14. When the plug 22 is present, as shown, it reinforces the tool and resistsany tendencyto distort the spring arms 14.

Whereas the preferred form of the invention has been shown and described herein, it should be realized that there are many modifications, substitutions and alterations thereto within the scope of the following claims.

We claim:

1. A bolt tool comprising a generally tubular member and a plurality of'integral, oirc-nmferentially spaced spring finger elements positioned about said member, said spring finger elements provided in their free ends internally with boltagripping conformations, a hollow sleeve, said sleeve being positioned about said tubular member and slidable therealong and dimensioned when in one position to force said spring fingers inwardly, portions of the inner surfaces of said spring fingers being angular within the volume bounded by said spring fingers and shaped generally to fit within and to engage said angular surfaces. a 2. A bolt tool comprising a generally tubular member 7 and a plurality of integral, circumferentially'spaced spring is moved. again to the upper position of FIG; 1, and the 14 are separated manually or by means of a tool, or otherwise, so that they are moved out of engagement with the head of the screw and the tool is removed. When this has taken place the screw will remain in position of engagement within the member into which it has been screwed. a

' If it is desired to remove the, screw, the tool is again inserted into the counterbore or cup with the tool parts in the position of FIG. 1. When the parts are in that position the arms 14 may be sprung apart sufiiciently to engage the head of the screw. After engagement has been accomplished the tubular member 25 is moved downwardly to the position of FIG. 2 and thenby means of the handle 3.0, 31 the tool and screw may be rotated inthe reverse direction so as to remove the screw from the threaded hole 20 and finally'to remove the screw completely. V,

' The plug 22 fitting within the tool and engaging generally at its upper and lower ends the angular portions of the inner surface of the tool is 'held relatively tightly in that position when the tool is engaging and holding the screw. Thus in the position of FIGS. 2 and 4 the plug}: is held relatively closely the tool. .When

v the parts are position and the tool is rotated the V .tortional interlock therewith.

finger elements positioned about said member and biased to move outwardly, each of said spring finger elements provided in their free ends internally with bolt-gripping conformations, ahollow sleeve, said sleeve being positioned about said tubular member and slidable therealong and dimensioned when in one position to force said spring fingers inwardly,'portions of the inner surfaces of said spring fingers being angular in cross section, and a plug member positioned loosely within the volume bounded by said spring fingers and shaped generallyto fit within and to engage said angular surfaces.

3. A bolt tool comprising a generally tubular membe; and a plurality of circumferentially-spaced spring finger elements positioned about said member, said spring finger elements being biased outwardly and having an internal bolt-gripping conformation at their free ends, means, slideable on said tubular'member, toforce said spn'ng fingers inwardly to a bolt-gripping position, a

I plug member positioned within said spring'fingers, por- 'tions of the inner surfaces of said spring fingers being formed to engage said plug member and to prow'de a References Cited in the file of this patent UNITED STATES PATENTS 641,191 Champion Ian. 9, 1900 1,205,883 Gay Nov. 21, 1916 1,232,735 Torvik' July lO, 1917 1,294,552 Smith Feb. 18, 1919 1,326,454 Jones .Q Dec. 30, 1919 2,579,438 Longfellow Dec. 18,1951 2,800,829 West July 30, 1957 r 2,800,936 West July 30, 1957 Iamgotchian July 21, 1959 

